Su, Shuang (2011) *Asynchronous Signal Processing for Compressive Data Transmission.* Master's Thesis, University of Pittsburgh.

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## Abstract

In this thesis we propose a power-efficient procedure useful in the acquisition of biological data in digital form without using high frequency samplers. The data is compressed so that transmission is limited to parts of the signal that are significant. Our procedure uses an asynchronous sigma delta modulator (ASDM) together with a time-to-digital converter (TDC) to obtain binary data that is transmitted via orthogonal frequency division multiplexing (OFDM). The asynchronous sigma delta modulator is a nonlinear feedback system that allows the representation of bounded signals by zero-crossing times of a binary signal. Using duty-cycle modulation, the ASDM is shown to be equivalent to an optimal level-crossing sampler. The zero-crossing times are measured with a time-to-digital converter that applies pulse-shrinking delay lines and requires no high-frequency clock. Reconstruction of the original signal is possible from the zero-crossing times of the ASDM output binary signal. ASDM time-domain compression is compared with discrete wavelet transform based data compression. For wireless data transmission, the orthogonal frequency division multiplexing (OFDM) reduces the bit error-rate in multipath fading channels. The performance of the proposed algorithm is illustrated using an electrocardiogram signal, which fits the bursty characteristic appropriate for our procedure.

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## Details | |||||||||

Item Type: | University of Pittsburgh ETD | ||||||||
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Creators/Authors: |
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Title: | Asynchronous Signal Processing for Compressive Data Transmission | ||||||||

Status: | Unpublished | ||||||||

Abstract: | In this thesis we propose a power-efficient procedure useful in the acquisition of biological data in digital form without using high frequency samplers. The data is compressed so that transmission is limited to parts of the signal that are significant. Our procedure uses an asynchronous sigma delta modulator (ASDM) together with a time-to-digital converter (TDC) to obtain binary data that is transmitted via orthogonal frequency division multiplexing (OFDM). The asynchronous sigma delta modulator is a nonlinear feedback system that allows the representation of bounded signals by zero-crossing times of a binary signal. Using duty-cycle modulation, the ASDM is shown to be equivalent to an optimal level-crossing sampler. The zero-crossing times are measured with a time-to-digital converter that applies pulse-shrinking delay lines and requires no high-frequency clock. Reconstruction of the original signal is possible from the zero-crossing times of the ASDM output binary signal. ASDM time-domain compression is compared with discrete wavelet transform based data compression. For wireless data transmission, the orthogonal frequency division multiplexing (OFDM) reduces the bit error-rate in multipath fading channels. The performance of the proposed algorithm is illustrated using an electrocardiogram signal, which fits the bursty characteristic appropriate for our procedure. | ||||||||

Date: | 19 September 2011 | ||||||||

Date Type: | Completion | ||||||||

Defense Date: | 13 July 2011 | ||||||||

Approval Date: | 19 September 2011 | ||||||||

Submission Date: | 13 July 2011 | ||||||||

Access Restriction: | No restriction; The work is available for access worldwide immediately. | ||||||||

Patent pending: | No | ||||||||

Institution: | University of Pittsburgh | ||||||||

Thesis Type: | Master's Thesis | ||||||||

Refereed: | Yes | ||||||||

Degree: | MSEE - Master of Science in Electrical Engineering | ||||||||

URN: | etd-07132011-172042 | ||||||||

Uncontrolled Keywords: | Asynchronous sigma delta modulation; data compression; orthogonal frequency division multiplexing; time-to-digital converter | ||||||||

Schools and Programs: | Swanson School of Engineering > Electrical Engineering | ||||||||

Date Deposited: | 10 Nov 2011 14:51 | ||||||||

Last Modified: | 20 Jan 2012 16:11 | ||||||||

Other ID: | http://etd.library.pitt.edu/ETD/available/etd-07132011-172042/, etd-07132011-172042 |

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